Articles such as disposable absorbent garments have numerous application including diapers, training pants, feminine care products, and adult incontinence products. A typical disposable absorbent garment is formed as a composite structure including an absorbent assembly disposed between a liquid permeable bodyside liner and a liquid impermeable outer cover. These components can be combined with other materials and features such as elastic materials and containment structures to form a product which is specifically suited to its intended purposes.
For example, one such garment is a child's diaper, which has a central absorbent chassis and front and back side panels extending laterally out from the chassis adjacent longitudinally opposite ends thereof. A portion of each of the front and back side panels has a respective fastening component disposed thereon. During manufacture of the diaper, the central absorbent chassis is initially formed generally flat and then folded over so that the front and back side panels face each other. The respective fastening components of the front and back side panels are then aligned and connected together to define an engagement seam. Upon securing the front and back side panel fastening components together, the pre-fastened diaper is in its fully assembled three-dimensional form having an interior space bounded in part by the engagement seam.
Absorbent garments may be formed from a woven web material or a non-woven web material. A non-woven web is a web having a structure of individual fibers or threads which are interlaid, but not in a regular or identifiable manner as in a knitted or woven fabric. The term also includes individual filaments and strands, yarns or tows as well as foams and films that have been fibrillated, apertured, or otherwise treated to impart fabric-like properties. Non-woven fabrics or webs have been formed from many processes such as for example, meltblowing processes, spunbonding processes, and bonded carded web processes.
The failure to properly control woven or non-woven fabrics supplied to a manufacturing process can result in quality concerns, additional material costs, and defective products. In order to avoid defects when forming diapers from web material, it is important that the web width be controlled during the manufacturing process. The importance of web width control becomes apparent when other components (e.g., ears) must be tacked onto a sausage of the non-woven web material. Defective absorbent garments can result from improper width alignment of the sausage components. One method of controlling web width involves monitoring and controlling web tension during manufacturing. However, this method often proves inadequate in controlling width variability. As a result, diaper manufacturing tolerances are widening.
In spite of past efforts, there is a need for improved methods and systems for controlling web width variability during a manufacturing process. There is a need for systems and methods that permit monitoring and controlling web width during manufacturing.
The invention described below addresses one or more of these and other disadvantages and needs.